My mother is 60+ years old and 200+ lbs. She never learned to ride a bicycle, so she rides a Schwinn Town & Country adult tricycle. She loves it and rides it everyday, 2-5 miles everyday. The spokes on the rear right wheel keep breaking. In the past year, since she's had the trike, she must have had 5-10 spokes replaced. The right wheel is also the "Drive" wheel, and the only wheel giving her problems. Could it be a shoddy wheel? a bad wheel builder?

What could be done to fix this? Stronger spokes? Replace the whole wheel for a new one?

4 Answers
4

I am assuming that it is the spokes are breaking at the hub.
On a drive side wheel, that is where they always break.

There is a different rare condition, when the spoke nipples are breaking off at the rim.
Rims have two sets of holes, one set on the each side.
The spokes might be laced to the opposite side of the rim.
I have never seen this from any bike factory, but rather from amateur wheel builders.

When a wheel starts breaking spokes, the spokes are almost always to blame.
Aged galvanized spokes that are gray or rusty can have all kinds of microscopic corrosion fractures at the bend. If the spokes are not corroded, or were made of stainless steel, it could even just be a bad batch of spokes.

Even if a bad wheel build was the original cause, the remaining spokes are damaged and will break with continued use. Re-tensioning the old damaged spokes won't help.

I am surprised the bike shop replaced the spokes one at a time after the second time it came back. If the wheel is breaking spokes, it will continue breaking spokes until the entire set of spokes is replaced.

There is one other possibility with three wheelers.
I have not seen a Schwinn three wheeler up close for 15 years or so, but in the old days they had chromed steel hubs, and those can sometimes be a problem.

If the steel hub has a sharp edge in the spoke hole, that is a stress riser.
The spokes break right where the spoke bend hits the sharp corner. Aluminum hubs are softer and will deform a bit - no sharp edge, no stress riser, no breakage.

The drive wheel on a three wheeler uses a special hub, special made for that exact trike, so you are pretty much stuck with the hub it came with.

I have lightly chamfered the spoke holes in some problem steel hubs with a countersink bit to remove that sharp edge. A dab of paint to avoid rust is useful too.

While the chamfering makes logical sense, and those wheels never came back, it is hard to tell if the chamfering did the trick, or if a set of new high quality stainless spokes was enough to cure the problem.

If the trike is only a year old, it should be a warranty repair to get a proper fix, not just one spoke at a time. Either replace all the spokes with quality stainless spokes, or replace the wheel. I would trust a new set of spokes more than a replacement wheel. If the shop won't handle this under warranty for a one year old trike, then contact the shop owner, or go up to Schwinn corporate if you need to.

If you've got spokes that keep breaking, either the wheel was originally built poorly or the wheel just isn't strong enough ( poor quality materials to begin with, etc ).

The cost of having a professional take the time and care to properly re-tension all of the spokes and get the wheel in shape might be prohibitive, and theres a chance it might not solve your problem for good. You may save yourself some time money and effort by just getting a stronger higher quality wheel.

Based on the pictures on the web, that's a fairly standard 3-cross wheel. You can try replacing the entire wheel, but the new one may not be any better. The other option is to have the wheel rebuilt with high-quality spokes.

It depends a bit on the history of the bike. If it's fairly old (more than 5 years or so) and the failing spokes in something new then it's likely just age and fatigue (and possibly corrosion from being out in the weather). In such a case simply replacing the wheel is probably the cheapest option.

But if the spokes have been failing regularly all along it's likely that the spokes are poor quality and rebuilding the wheel with better spokes would be the better option.,

I mostly agree with you. I think the original wheel may have been poorly built, or sustained major trauma which critically stressed many or all of the spokes. They are failing one by one just as they would if the wheel were old. It's hard to say without seeing the riding style, but I find it difficult to believe a 200+ lb, 60 women on a tricycle is putting the wheel through that much torture. The biggest stress is her weight which is split between 3 26" wheels. The lateral stress much be larger than on a bicycle, but it can't be that much larger.
–
GlennNov 19 '12 at 18:11

Its easier to keep replacing the spokes. When riding on uneven surfaces your weight shifts from side to side on the rear wheels,turning corners at a higher speed,bumping into curbs with front wheel while turning can also break spokes.I ride a Meridian 26" & started snapping spokes at first,I always kept 20 spare spokes on hand & I think the new ones may be better than the Schwinn spokes because I haven't broke any for a while,replacing rims from Pacific Cycles is good if your rims are bent bad,I've replaced axles,rims,bearings but I started at 400 lbs.I ride 2-3 times a day.Love my Trike, I just wish I could make it 5-6 speed instead of the 3 speed hub I have now( don't climb well enough )tomorrow I get my Serfas 14" wide cruiser saddle.my trike has a canopy shade cover,stereo,alarm,turn signals,brake lights,cane holder,white wall tires & a wooden trunk. I call It my Schwinn Cadillac.